FR2995372A1 - FIXING DEVICE - Google Patents

Abstract

The invention relates to a fixing device (100) comprising: - a rod (107) extending along an axis (104) and comprising a head (108) and a shank (109); - A sleeve (111) extending along the axis of the rod and having a head (112) adapted to receive the head of the rod and a body (113) adapted to receive the shaft of the rod, the body of the sleeve having an internal diameter smaller than a diameter of the shank of the shank, so as to provide a negative clearance between the socket and the shank; - A ring (116) made of solid and compressible material, integral with an outer surface (115) of the body of the sleeve and disposed near the head of the sleeve.

Description

The present invention relates to a fastening device. The invention finds its application more particularly, but not exclusively, in the aeronautical field. It is known from the prior art a fixing device, intended for mounting in interference with a structure, comprising a screw extending along an axis and comprising a head and a shaft, and a sleeve extending along the the axis of the screw and comprising a body accommodating the barrel of the screw and a head blocking a translation of the sleeve along the axis of the screw when the sleeve is in place in a bore. An interference montage is a montage with a negative game. In the aforementioned prior art, the shank of the screw has an external diameter greater than the internal diameter of the sleeve that will receive it, which causes a radial expansion of the socket in the bore during the installation of the screw. , sufficient to block any translational movement of the expanded fastener in the bore. Such a fixing device is for example described in document WO 2010/142901. Such a fixing device is conventionally assembled to a structural element comprising a bore disposed along the axis of the screw. Now, the bushing and the bore are generally configured so that a gap is formed between a radius under the head of the bushing and a radius of entry of the bore. Such an interstice makes it possible to guarantee a total approach of the head of the socket on the structure. It is known from the prior art to deposit a layer of fresh mastic on a part of the structural element intended to come into contact with the underside of the head of the sleeve, so as to ensure fluid tightness, like water or fuels, assemble once the sealant is dry. However, during the step of placing the bushing in the bore, fresh sealant may become lodged in the gap formed between the under-head radius of the bushing and the entrance radius of the bore. When the screw is inserted into the socket and the radius under the head of the sleeve expands radially, the sealant is expelled from the gap in the bore, and is spread around the body of the sleeve. The presence of fresh sealant around the bushing body is particularly problematic because a lubricant film is formed between the bushing body and the bore, affecting the adhesion between the bushing and the drill. However, if the adhesion between the screw and the bushing becomes greater than the adhesion between the bushing and the bore, the bushing is driven by the screw and lengthens as the screw is inserted.

Such elongation of the bushing causes for example a thinning and embrittlement of the area under the head of the bushing, but also an incomplete radial expansion of the bushing and therefore a lower interference between the bushing and the bore. The presence of sealant around the body of the bushing therefore considerably affects the quality of the assembly, particularly as regards mechanical strength. There is therefore a need to prevent the fresh sealant layer from spreading around the body of the socket. One aspect of the present invention solves this technical problem.

More specifically, the invention relates to a fixing device comprising a rod extending along an axis and comprising a head and a shaft; a sleeve extending along the axis of the rod and having a head adapted to receive the head of the rod and a body adapted to receive the shaft of the rod, the body of the sleeve having an internal diameter less than a diameter of the barrel of the stem, so as to provide a negative clearance between the sleeve and the barrel; and a ring of solid and compressible material, integral with an outer surface of the body of the sleeve and disposed near the head of the sleeve. Preferably, the ring is formed of a material comprising an acrylic polymer.

More preferably, the ring is formed of a material further comprising mica.

Preferably, the ring is arranged around a radius under the head of the socket. Preferably, the rod is a screw or a rivet comprising a pulling tail.

The invention also relates to a method of manufacturing a device as previously described, comprising a step of depositing, on the outer surface of the sleeve, a bead of a polymeric material in the liquid or viscous state. then a polymerization to solidify said material in the form of a ring.

The invention also relates to a method of assembling a fixing device as previously described to a structural element comprising a bore adapted to receive the sleeve with play, said method comprising a step of depositing a layer of a viscous or liquid composition on a part of the structural element intended to come into contact with the head of the socket; a step of placing the bushing in the bore of the structural element along the axis of the screw, so that the ring comes in compression against the drilling; then a step of inserting the rod in the sleeve along the axis of the rod, so that the sleeve expands radially in the bore and the ring compresses against the bore. The invention also relates to an assembly of a fixing device and an assembly element, said assembly being derived from a method as previously described. The invention will be better understood on reading the description which follows and on examining the figures which accompany it. These are presented as an indication and in no way limitative of the invention. The figures show: FIG. 1: a schematic, exploded and sectional view of a fastening device and two structural elements before assembly, according to one embodiment of the invention; - Figure 2 is a schematic, exploded and sectional view of a fixing device and two structural elements before assembly, according to another embodiment of the invention; - Figure 3: a schematic, exploded and sectional view of a fixing device and two structural elements before assembly, according to another embodiment of the invention. FIG. 1 represents a schematic view of a fixing device 100, a first structure element 101 and a second structure element 102 according to one embodiment of the invention.

The structural elements (101, 102) comprise a bore 103 disposed along an axis 104. In the example shown in FIG. 1, the bore 103 comprises a countersink 105 and a cylindrical bore 106 passing through the first and second elements (101, 102) of structure. The fixing device 100 comprises a screw 107 extending along the axis 104. The screw 107 comprises a countersunk head 108, a frustoconical barrel 109 and a threaded portion 110 disposed opposite the head 108. The device 100 of FIG. fixation also comprises a sleeve 111 extending along the axis 104. The sleeve 111 is able to be inserted into the bore 103.

The sleeve 111 comprises a head 112 adapted to receive the head 108 of the screw 107. In the example shown in Figure 1, the head 112 of the sleeve 111 is of milled form. The bushing 111 further includes a body 113 adapted to receive the barrel 109 of the screw 107. An inner surface 114 of the body 113 of the bushing 111 is of substantially complementary shape with the barrel 109 of the screw 107. Thus, in FIG. As shown in FIG. 1, the internal surface 114 of the body 113 is of frustoconical shape. An outer surface 115 of the body 113 of the sleeve 111 is of substantially complementary shape with the bore 106 of the bore 103. Thus, in the example shown in Figure 1, the outer surface 115 of the body 113 is cylindrical. The fixing device 100 is intended to be mounted in the interfering structure elements (101, 102). In the example shown in FIG. 1, the interference assembly is carried out as follows. The barrel 109 of the screw 107 has, at the same height along the axis 104, a diameter greater than a diameter of the internal surface 114 of the body 113 of the bushing 111, so that the insertion of the screw 107 in the bushing 111 causes radial expansion of said bushing. A diameter of the outer surface 115 of the bushing 111 is, before insertion of the screw 107, less than a diameter of the bore 106 of the bore 103, so that the bushing 111 is introduced into the bore 103 with a positive clearance. . Finally, the insertion of the barrel 109 of the screw 107 into the bushing 111 causes the expansion of the outer diameter of said bushing, so as to ensure the locking of the fastening device 100 along the axis 104. The fastening device 100 comprises furthermore, a ring 116 made of solid and compressible material. The ring 116 is integral with the outer surface 115 of the body 113 of the sleeve 111. The ring 116 is close to the head 112 of the sleeve 111. Preferably, the ring 116 is disposed at a radius 117 under the head of the sleeve 111, that is to say at the intersection between the head 112 and the body 113 of the sleeve 111. The ring 116 is configured so as to be pressed against the bore 103. The countersink 105 of the piercing 103 is coated with a layer 118 of a composition, in the viscous or liquid state before installation of the fixing device 100 in the piercing 103. The composition in the viscous or liquid state is, for example fresh putty . Preferably, the fresh mastic layer 118 is disposed over the entire periphery of the countersink 105 so as to seal the assembly of the fastener 100 and the first and second structural members (101, 102). Figure 2 shows another embodiment of the invention in which similar elements retain the same references to which the letter A is added. The features common with the embodiment of Figure 1 will not be developed again in the following description. Figure 2 shows a schematic view of the attachment device 100A, and first and second structural members (101A, 102A) including a bore 103A. In the example shown in Figure 2, the bore 103A is a cylindrical bore. The screw 107A of the fixing device 100A comprises a protruding cylindrical head 108A, a barrel 109A of cylindrical shape, and a threaded portion 110A disposed opposite the head 108A. The bushing 111A of the fixing device 100A is provided with a head 112A and a body 113A whose internal surface 114A and external surface 115A are cylindrical in shape. The diameter of the barrel 109A of the screw 107A is larger than the diameter of the inner surface 114A of the body 113A of the sleeve 111A. The diameter of the outer surface 115A of the body 113A of the bushing 111A is smaller than the diameter of the bore 103A, before insertion of the screw 107A into the bushing 111A. Thus, the fixing device 100A allows the realization of a mounting in the elements (101A, 102A) structure with interference. The head 112A of the bushing 111A has the shape of a substantially flat flange disposed substantially perpendicular to the axis 104A of the screw 107A. When the fixing device 100A is assembled to the first and second structural members (101A, 102A), the flange 112A is clamped between a surface 119 of the first structural member 101A and the head 108A of the screw 107A.

A zone 120 of contact between the collar 112A and the surface 119 of the first structural element 101A is provided with the layer 118A of fresh mastic. Preferably, the layer 118A of fresh mastic is disposed over the entire periphery of the zone 120 of contact of the flange 108A, so as to seal the assembly of the fixing device 100A and the first and second elements (101A, 102A) of structure.

The ring 116A is disposed at the level of the beam 117A under the head of the bushing 111A, on the outer surface 115A of the body 113A of the bushing 111A. FIG. 3 shows another embodiment of the invention in which the elements similar to FIGS. 1 and 2 retain the same references to which the letter B is added, and the elements similar to FIG. 2 only retain the same references to which the letter C is added. The features common with the embodiments of Figures 1 and 2 will not be developed again in the following description.

Figure 3 shows a schematic view of the attachment device 100B, and first and second structural members (101B, 102B) including a bore 103B. In the example shown in Figure 3, the hole 103B is a cylindrical bore. The fixing device 100B comprises a rivet 107B comprising a protruding head 108B, a cylindrical barrel 109B, a blocking portion 121 and a traction shank 122. The pulling shank 122 is disposed opposite the head 108B of the rivet 107B, and the locking portion 121 is disposed between the shank 109B and the pulling shank 122. In the example shown in Figure 3, the blocking portion 121 is made in the form of crimping grooves. The bushing 111B of the fixing device 100B is similar to the bushing 111A shown in FIG. 2. The bushing 111B is provided with a head 112B in the form of a flange and a body 113B whose surfaces (114B, 115B ) internal and external are cylindrical. Thus, similarly to the example shown in FIG. 2, the zone 120C of contact between the flange 112B and the surface 119C of the first structural element 101B is provided with the layer 118B of fresh mastic. The diameter of the barrel 109B of the rivet 107B is larger than the diameter of the inner surface 114B of the body 113B of the sleeve 111B. The diameter of the outer surface 115B of the body 113B of the bushing 111B is smaller than the diameter of the bore 103B, before insertion of the rivet 107B into the bushing 111B. Thus, the fixing device 100B allows the realization of a mounting in the elements (101B, 102B) structure with interference. In a variant, the head 108B of the rivet 107B is milled, and / or the blocking portion 121 is made in the form of a thread capable of receiving a nut. The ring 116B is disposed at the level of the beam 117B under the head of the bushing 111B, on the outer surface 115B of the body 113B of the bushing 111B. Such assemblies have the advantage of blocking an expansion of the fresh sealant layer towards the outer surface of the body of the sleeve by means of the ring compressed between the body of the sleeve and the bore, thus making it possible to prevent the adhesion between the bushing and the hole is compromised. The game that the ring (116, 116A, 116B) has to fill is very weak and variable. Therefore, the ring preferably has a crushing capacity large enough not to hinder the proper mounting of the fixing device in the bore and in particular do not limit the radial expansion of the sleeve in the bore. The ring (116, 116A, 116B) also has a good compressive strength, so as not to crack or grind, when tightening the fastener in the structural members. A material particularly meeting these constraints is in particular based on acrylic polymer. The material may also include mica. Tables 1 and 2 each show an example of a sealant composition particularly suitable for the manufacture of the ring (116, 116A, 116B). Components CAS Number% Acrylic Polymer - 10 - 30 Mica 12001-26-2 5 - 10 Titanium Dioxide 13463-67-7 1 - 5 Acrylic Polymer 25212-88-8 1 - 5 Quartz (Si02) 14808-60-7 0.1 1- (3-Chloroallyl) -3,5,7-triaza-1- 4080-31-3 0.1 - 1 azonia-adamantane chloride Table 1 Components CAS number% Acrylic Polymer - 10 - 30 Mica 12001-26 -2 5 - 10 Difer trioxide 1309-37-1 1 - 5 Titanium dioxide 13463-67-7 1 - 5 Acrylic polymer 25212-88-8 1 - 5 Propanedio1-1,2 57-55-6 1 - 5 Quartz (SiO2) 14808-60-7 0.1 - 1 1- (3-Chloroallyl) -3,5,7-triaza-1- 4080-31-3 0.1 - 1 azonia-adamantane chloride Table 2 Vibra-seal compositions ® 503 and Vibra-seal® 516 sold by Loctite are examples of suitable compositions for the manufacture of the ring (116, 116A, 116B). These compositions are known in the fastening industry and used by application to the screw threads. Once cured, these compositions seal the screw / nut fasteners at their threads in engagement, and limit or prevent the nuts from loosening when screwed onto screw threads coated with one of these threads. compositions. The Applicant has found that these compositions, when dry, have a porous composition particularly suited to the problem that the present invention aims to solve, unlike plastic or rubber seals which have a limited crushing capacity and a low resistance to the compression. Thus, once dried, the composition adapts to the defect of shapes and volume variations by compressing without cracking or grinding, and by not influencing very little, which does not compromise the integrity of the installation in interference.

The ring (116, 116A, 116B) is for example manufactured by depositing on the sleeve a bead of fresh mastic corresponding to the composition of Table 1 or Table 2, then by carrying out a polymerization at room temperature, or by cooking for accelerate the polymerization process. Once the bead is cured, the fastener can be mounted in the structural members. A method for forming the assemblies described above is as follows. The layer (118, 118A, 118B) of fresh mastic is first deposited on a portion (105, 120, 120C) of the first structural member (101, 101A, 101B) for receiving the head (112, 112A, 112B). ) of the bushing (111, 111A, 111B). In the example shown in FIG. 1, the layer 118 is deposited on the countersink 105 of the piercing 103. In the examples presented in FIGS. 2 and 3, the layer (118A, 118B) is deposited on the zone (120, 120C). contact between the collar (112A, 112B) of the bushing (111A, 111B) and the surface (119, 119C) of the first structural element (101A, 101B), when the bushing (111A, 111B) is in place in the piercing (103A, 103B). The rivet 107B or the screw (107, 107A) is then partially inserted into the sleeve (111, 111A, 111B). By "partial insertion" is meant that the rivet or screw is inserted without force or with a limited force into the socket. Thus, the partial insertion of the rivet or the screw into the socket does not cause the radial expansion of the socket. Typically, when the screw or rivet is partially inserted into the socket, the shank (109, 109A, 109B) of the screw or rivet spring at least in part from the socket. Similarly, the threaded portion (110, 110A) of the screw or the pulling shank 122 of the rivet partially emerges from the socket. Then, the fixing device (100, 100A, 100B), comprising the rivet 107B or the screw (107, 107A) partially inserted into the socket, is put in place with a positive clearance in the bore (103, 103A, 103B). , so that the head (112, 112A, 112B) of the sleeve (111, 111A, 111B) comes into contact with the layer (118, 118A, 118B) of fresh mastic. The ring (116, 116A, 116B) is compressed slightly against the bore (103, 103A, 103B), thereby blocking the expansion of the fresh putty layer (118, 118A, 118B) towards the surface (115, 118A, 118B). 115A, 115B) of the body (113, 113A, 113B) of the sleeve (107, 107A, 107B). In the examples presented in FIGS. 1 and 2, a nut (123, 123A) is placed on the threaded portion (110, 110A) of the screw (107, 107A) and then tightened, causing the screw to be fully inserted into the bushing (111, 111A). The screw is considered completely inserted when the head (108, 108A) of the screw is in contact with the head (112, 122A) of the socket. Insertion of the screw (107, 107A) causes the radial expansion of the sleeve (111, 111A) and the final compression of the ring (116, 116A). In the example shown in Figure 3, a tool is used to pull the pulling shank 122 to fully insert the rivet 107B into the socket 111B. The rivet is considered completely inserted, when the head 108B of the rivet is in contact with the head 112B of the socket. The insertion of the rivet 107B causes the radial expansion of the bushing 111B and the final compression of the ring 116B. Depending on the type of rivet used, a ring 123B is crimped on the blocking portion 121 and then the pulling tail 122 is broken, or the rivet is broken then the ring 123B is crimped on the blocking portion 121. According to a variant in which the locking portion 121 is a thread, a nut is tightened on the thread. Finally, a final step is to allow the assembly to dry so that the sealant of the layer (118, 118A, 118B) solidifies to ensure the tightness of the assembly.

Such an assembly method has the advantage of preventing the fresh mastic layer (118, 118A, 118B) from extending inside the bore, around the body (113, 113A, 113B) of the sleeve ( 111, 111A, 111B). In this way, the adhesion between the bushing (111, 111A, 111B) and the bore (103, 103A, 103B) necessary for a good quality of the assembly of the fastening device (100, 100A, 100B) and the elements structure is assured.

Claims (8)

CLAIMS1 - Fixing device (100, 100A, 100B) comprising: - a rod (107, 107A, 107B) extending along an axis (104, 104A, 104B) and comprising a head (108, 108A, 108B) and a barrel (109, 109A, 109B); - A sleeve (111, 111A, 111B) extending along the axis of the rod and having a head (112, 112A, 112B) adapted to receive the head of the rod and a body (113, 113A, 113B) fit receiving the shank of the shank, the body of the shank having an internal diameter smaller than a diameter of the shank of the shank, so as to provide a negative clearance between the shank and the shank; said device being characterized in that it further comprises a ring (116, 116A, 116B) of solid and compressible material, integral with a surface (115, 115A, 115B) external to the body of the sleeve and arranged near the the head of the socket. 2 - Device according to claim 1, wherein the ring is formed of a material comprising an acrylic polymer. 3 - Device according to claim 2, wherein said material further comprises mica. 4 - Device according to one of the preceding claims, wherein the ring is arranged around a spoke (117, 117A, 117B) under the head of the sleeve. 5 - Device according to one of the preceding claims, wherein the rod is a screw (107, 107A) or a rivet (107B) comprising a tail (122) of traction. 6 - A method of manufacturing a device (100, 100A, 100B) according to one of the preceding claims, comprising a deposition step on the outer surface (115, 115A, 115B) of the sleeve (111, 111A, 111B). ), a bead of a polymeric material in the liquid or viscous state, and then a polymerization to solidify said ring material (116, 116A, 116B). 7 - Method of assembling a device (100, 100A, 100B) for fixing according to one of claims 1 to 5 to a structural element comprising a bore (103, 103A, 103B) adapted to receive the sleeve (111 , 111A, 111B) with a clearance, said method comprising the steps of: depositing a layer (118, 118A, 118B) of a viscous or liquid composition on a portion (105, 120, 120C) of the structure for engaging the head (112, 112A, 112B) of the socket; - placing the bushing in the bore of the structural element along the axis (104, 104A, 104B) of the rod (107, 107A, 107B), so that the ring (116, 116A, 116B ) come in compression against drilling; - Insertion of the rod in the sleeve along the axis of the rod, so that the sleeve expands radially in the bore and the ring compresses against drilling. 8 - Assembly of a device (100, 100A, 100B) for fixing and an assembly element, said assembly being derived from a method according to claim 7.